[ncl-talk] time_to_newtime vs. cd_convert
Mary Haley
haley at ucar.edu
Thu Oct 9 16:50:27 MDT 2014
I've filed a ticket on this, NCL-2029.
It does seem like they are similar. I think time_to_newtime is an older
function, so it may be that we just deprecate that one and go with
"cd_convert".
--Mary
On Tue, Oct 7, 2014 at 7:20 AM, Alan Brammer <abrammer at albany.edu> wrote:
> I agree it seems like they could be combined and if one wants to
> change/keep the calendar it could be attached to the units string as an
> attribute. As neither version handles this at the moment it shouldn't
> affect compatibility.
>
> Alan.
> On 7 Oct 2014 06:59, "Carl Schreck" <cjschrec at ncsu.edu> wrote:
>
>> Related question... What's the difference between cd_convert and
>> time_to_newtime?
>>
>> Looking at the code, I think they just handle the metadata a little
>> differently. Notably, time_to_newtime updates the coordinate variable
>> (something I forgot to do when I originally wrote ut_convert).
>>
>> Perhaps they should be reconciled into one function and the other one
>> marked as deprecated or as an alias on the website?
>>
>> Carl
>>
>> On Mon, Oct 6, 2014 at 10:55 PM, Lam Hoang <lamhpvn at gmail.com> wrote:
>>
>>> Hi Alan,
>>> I'm using NCL 6.1.2 and your code works perfectly.
>>>
>>> Variable: t
>>> Type: double
>>> Total Size: 20440 bytes
>>> 2555 values
>>> Number of Dimensions: 1
>>> Dimensions and sizes: [time | 2555]
>>> Coordinates:
>>> time: [ 0.5..2554.5]
>>> Number Of Attributes: 6
>>> bounds : time_bnds
>>> units : days since 2006-01-01 00:00:00
>>> calendar : noleap
>>> axis : T
>>> long_name : time
>>> standard_name : time
>>>
>>> Variable: t
>>> Type: double
>>> Total Size: 20440 bytes
>>> 2555 values
>>> Number of Dimensions: 1
>>> Dimensions and sizes: [time | 2555]
>>> Coordinates:
>>> time: [56940.5..59494.5]
>>> Number Of Attributes: 6
>>> calendar : noleap
>>> units : days since 1850-01-01 00:00:00
>>> bounds : time_bnds
>>> axis : T
>>> long_name : time
>>> standard_name : time
>>>
>>> Best regards,
>>> Lam
>>>
>>> On Tue, Oct 7, 2014 at 5:07 AM, Alan Brammer <abrammer at albany.edu>
>>> wrote:
>>>
>>>> What version of ncl are you using? I just tested a similar few lines of
>>>> code in 6.1.1 and 6.2.0 and they both copied the calendar attribute as
>>>> expected. Also have you tried cd_convert() seems to do the same thing?
>>>>
>>>> However in these tests and looking around I have a strong suspicion
>>>> there is a significant bug in this function. In that the code copies the
>>>> calendar attribute but does not actually make use of it and thus returns
>>>> the wrong answer disguised as the correct one.
>>>>
>>>>
>>>> Attached is my edited code. load this below a load
>>>> "....contibuted.ncl" line if you have one and this version of the code will
>>>> replace the stock version. A developer will hopefully weigh in with more
>>>> insight in this.
>>>>
>>>>
>>>> Good luck,
>>>>
>>>> Alan
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Oct 3, 2014 at 10:08 PM, Lam Hoang <lamhpvn at gmail.com> wrote:
>>>>
>>>>> Dear NCL supporting team,
>>>>> I want to convert the time units from a CMIP5 model to make them
>>>>> unique.
>>>>> I try to use time_to_newtime function but unfortunately after convert
>>>>> the time units, the calendar attribute changes to "gregorian" as well.
>>>>> What should I do if I want to keep the calendar attribute as the
>>>>> original time variable?
>>>>>
>>>>> Regards,
>>>>> Lam
>>>>>
>>>>>
>>>>> f =
>>>>> addfile("./oldtime_psl_day_NorESM1-M_historicalExt_r3i1p1_20060101-20121231.nc","r")
>>>>> temp = f->psl
>>>>> t = f->time
>>>>>
>>>>> printVarSummary(t)
>>>>>
>>>>> *** Variable: t
>>>>>
>>>>> *** Type: double
>>>>>
>>>>> *** Total Size: 20440 bytes
>>>>>
>>>>> *** 2555 values
>>>>>
>>>>> *** Number of Dimensions: 1
>>>>>
>>>>> *** Dimensions and sizes: [time | 2555]
>>>>>
>>>>> *** Coordinates:
>>>>>
>>>>> *** time: [ 0.5..2554.5]
>>>>>
>>>>> *** Number Of Attributes: 6
>>>>>
>>>>> *** bounds : time_bnds
>>>>>
>>>>> *** units : days since 2006-01-01 00:00:00
>>>>>
>>>>> *** calendar : noleap
>>>>>
>>>>> *** axis : T
>>>>>
>>>>> *** long_name : time
>>>>>
>>>>> *** standard_name : time
>>>>>
>>>>> t = time_to_newtime(t, "days since 1850-01-01 00:00:00")
>>>>>
>>>>> printVarSummary(t)
>>>>>
>>>>> *** Variable: t
>>>>>
>>>>> *** Type: double
>>>>>
>>>>> *** Total Size: 20440 bytes
>>>>>
>>>>> *** 2555 values
>>>>>
>>>>> *** Number of Dimensions: 1
>>>>>
>>>>> *** Dimensions and sizes: [time | 2555]
>>>>>
>>>>> *** Coordinates:
>>>>>
>>>>> *** time: [56978.5..59534.5]
>>>>>
>>>>> *** Number Of Attributes: 6
>>>>>
>>>>> *** calendar : gregorian
>>>>>
>>>>> *** units : days since 1850-01-01 00:00:00
>>>>>
>>>>> *** bounds : time_bnds
>>>>>
>>>>> *** axis : T
>>>>>
>>>>> *** long_name : time
>>>>>
>>>>> *** standard_name : time
>>>>>
>>>>>
>>>>> --
>>>>> Hoang Phuc Lam
>>>>> Viet Nam National Center of Hydro-Meteorology Forecasting
>>>>> National Hydro-Meteorological Services of Vietnam
>>>>> Mob: +84 12 1616 5258
>>>>> Tel: +844 38247002
>>>>> Fax: +844 38254278
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> List instructions, subscriber options, unsubscribe:
>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> Hoang Phuc Lam
>>> Viet Nam National Center of Hydro-Meteorology Forecasting
>>> National Hydro-Meteorological Services of Vietnam
>>> Mob: +84 12 1616 5258
>>> Tel: +844 38247002
>>> Fax: +844 38254278
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>>
>>
>>
>> --
>>
>> <http://www.cicsnc.org/>
>> <http://www.researcherid.com/rid/B-8711-2011>
>> * Cyclone <http://www.cyclonecenter.org/>*Center.org
>> <http://www.cyclonecenter.org/> *Carl J. Schreck III, PhD*
>> *Research Associate*
>> Cooperative Institute for Climate and Satellites NC
>> <http://www.cicsnc.org/>
>> North Carolina State University <http://ncsu.edu/>
>> NOAA's National Climatic Data Center <http://ncdc.noaa.gov/>
>> 151 Patton Ave, Asheville, NC 28801
>> e: cjschrec at ncsu.edu
>> o: +1 828 257 3140
>> Publications
>> <http://scholar.google.com/citations?hl=en&user=th8ONEcAAAAJ&view_op=list_works&sortby=pubdate>
>> monitor.cicsnc.org/mjo
>>
>
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